Conventionally known pump-dispensing containers discharge a liquid contained in a container body from a discharge opening at the tip of a nozzle head disposed hi the upper part of the container body when the nozzle head is moved up and down. That type of pump-dispensing container usually has a liquid chamber (a gap between a cylinder and a piston) in a dispensing pump body and has a primary check valve and a secondary check valve respectively at the upstream end (on the container body side) and at the downstream end (on the discharge opening side) of the liquid chamber. When the nozzle head is raised, the secondary check valve is closed to depressurize the liquid chamber, and the depressurization opens the primary check valve, through which the liquid in the container body flows into the liquid chamber. When the nozzle is lowered, the liquid chamber is pressurized with the primary check valve kept closed, and the pressurization opens the secondary check valve, through which the liquid that has filled the liquid chamber is discharged from the discharge opening.
The secondary check valve that opens and closes the exit of the liquid chamber as the piston is lowered together with the nozzle head is generally designed, in that type of pump-dispensing container, to open immediately when the nozzle head is pressed down, and a slight press on the nozzle head opens the secondary check valve at the exit of the liquid chamber, causing the liquid to leak from the liquid chamber to the outside. Even if the pump-dispensing container is equipped with an over-cap or a stopper, for example, to prevent the nozzle head from being lowered from its highest position, when the containers contained in a carton box are placed upside down by mistake during transportation, the nozzle head may move up and down slightly due to vibration caused by uneven road surfaces and the like. In the container placed upside down by mistake, the primary check valve, which includes a ball valve, would be opened by gravity, and the liquid in the container body would flow into the liquid chamber. If vibrations during transportation move the nozzle head up and down further, causing the secondary check valve at the exit of the liquid chamber to open slightly, the liquid that has flown into the liquid chamber would leak from the discharge opening and would stain the containers in the carton box. There has been another problem that, when a pump-dispensing container in use is carried with its nozzle head placed in its highest position, only a slight vertical movement of the nozzle head would cause unintentional leakage of liquid, and extreme care should be used.
The present applicant has recently addressed those problems by proposing a pump-dispensing container in which a part supporting the lower end of a spring for pushing the piston upward can move up and down within a given range with respect to a cylinder, so that the secondary check valve will not be opened immediately when the nozzle head which has been placed in its highest position is lowered slightly (refer to Patent Literature 1). The secondary check valve that opens and closes the exit of the liquid chamber in the pump-dispensing container is usually configured to open when the spring is compressed; in the pump-dispensing container in Patent Literature 1, the part supporting the lower end of the spring is configured to allow a slight downward movement while the nozzle head is in its highest position. Accordingly, even if the nozzle head is moved slightly downward from the highest position, the spring does not start being compressed before the spring support comes into contact with the cylinder, or the top dead point (position where the spring starts being compressed) of the pump is reached. The secondary check valve will not open immediately, and consequently, unintentional leakage of liquid during transportation or the like can be avoided.